If you are playing the Classic Rules, then no, you can share on set of dice by simply passing the dice from player to player. But it’s more fun when each player has their own set.

When you are playing the Extra Spicy rules, you are allowed to start your next turn where you left off. For example, if you rolled four 5s and a red 6, you could choose not to flip the red 6 into a 5, and keep it instead to start your next turn. Obviously, you can’t share one set of dice in this case because the other players would roll your red 6, so you would need one set per player. Of course you can play Extra Spicy on your own for high score with just one set of dice.

Absolutely. Let’s say late in the game you roll a SET on your first roll, but SET is already taken. Maybe your SET included three white 4s, which are open. You could simply score the 4s as 12 points in the 4s box.

Now what if one of those was a red 4? Of course you could score the entire SET in the 4s box (undoubled), or you could score just the three 4s in 4s box (doubled) – which might be worth more points. Either option is legal.

And remember, you are allowed to shift scoring for RUNs and SETs even if the RUN or SET box are empty.